Due to the influence of mining disturbance stress,it is of great significance to better understand the bearing characteristics of fully grouted bolts under different pull-out loading rates.For this purpose,a series of...Due to the influence of mining disturbance stress,it is of great significance to better understand the bearing characteristics of fully grouted bolts under different pull-out loading rates.For this purpose,a series of laboratory pull-out tests were conducted to comprehensively investigate the effects of different pull-out loading rates on the mechanical performance and failure characteristics of fully grouted bolts.The results show that the mechanical performance of the anchored specimen presents obvious loading rate dependence and shear enhancement characteristics.With the increase of the pull-out loading rates,the maximum pull-out load increases,the displacement and time corresponding to the maximum pull-out load decrease.The accumulated acoustic emission(AE)counts,AE energy and AE events all decrease with the increase of the pull-out loading rates.The AE peak frequency has obvious divisional distribution characteristics and the amplitude is mainly distributed between 50-80 dB.With the increase of the pull-out loading rates,the local strain of the anchoring interface increases and the failure of the anchoring interface transfers to the interior of the resin grout.The accumulated AE counts are used to evaluate the damage parameter of the anchoring interface during the whole pull-out process.The analytical results are in good agreement with the experimental results.The research results may provide guidance for the support design and performance monitoring of fully grouted bolts.展开更多
The aim of the study was to investigate effect of transport times of up to 12 h on pigs＇ welfare. An observation box was located on the 3rd floor of the vehicle. Device to measure temperature, humidity and video came...The aim of the study was to investigate effect of transport times of up to 12 h on pigs＇ welfare. An observation box was located on the 3rd floor of the vehicle. Device to measure temperature, humidity and video camera to monitor pigs＇ behaviors were fitted in the box. Eighteen measurements were performed during two seasons for 4, 8, and 12 h of transport time with three replications. Meat samples were taken from longissimus dorsi （LD） and the carcases were chilled for 24 h at ＋4 ~C for pH determination. To determine cortisol, glucose, lactate, and creatine kinase concentration levels, blood samples were collected before and after transport from 90 pigs and from 20 controls that were not transported for control purposes. To evaluate behavioural alterations, frequency of events and durations were considered. Highest pH24 of 5.99 ＋ 0.29 occurred during summer at 12 h transport time. Cortisol concentrations elevated during short and decreased with an increase of transport time （P 〈 0.001）. Highest and lowest glucose concentrations for winter and summer were at 8 and 12 h transport time, respectively （P 〈 0.01）. Concentrations of lactate and creatine kinase positively correlated with transport time （P 〈 0.002）. Lying, sitting, rooting and vocalization behaviours correlated with transport time （P 〈 0.009）. Certain THI values during summer surpassed normal （〉 74） level during loading. The pH24 value correlated with transport time during summer. Lactate and creatine kinase concentrations increased with an increase in transport time but for Glucose, highest value was at 8 h transport time.展开更多
Cat vocal behavior, in particular, the vocal and social behavior of feral cats, is poorly understood, as are the differences between feral and fully domestic cats. The relationship between feral cat social and vocal b...Cat vocal behavior, in particular, the vocal and social behavior of feral cats, is poorly understood, as are the differences between feral and fully domestic cats. The relationship between feral cat social and vocal behavior is important because of the markedly different ecology of feral and domestic cats, and enhanced comprehension of the repertoire and potential information content of feral cat calls can provide both better understanding of the domestication and socialization process, and improved welfare for feral cats undergoing adoption. Previous studies have used conflicting classi- fication schemes for cat vocalizations, often relying on onomatopoeic or popular descriptions of call types （e.g., ＂miow＇）. We studied the vocalizations of 13 unaltered domestic cats that complied with our behavioral definition used to distinguish feral cats from domestic. A total of 71 acoustic units were extracted and visually analyzed for the construction of a hierarchical classification of vocal sounds, based on acoustic properties. We identified 3 major categories （tonal, pulse, and broadband） that further breakdown into 8 subcategories, and show a high degree of reliability when sounds are classified blindly by independent observers （Fleiss＇ Kappa K= 0.863）. Due to the limited behavioral contexts in this study, additional subcategories of cat vocalizations may be identified in the future, but our hierarchical classification system allows for the addition of new categories and new subcategories as they are described. This study shows that cat vocalizations are diverse and complex, and provides an objective and reliable classification system that can be used in future studies.展开更多
Unidirectional acoustic transmission has been investigated in an asymmetric bull's eye structure, which consistes of a subwavelength hole with concentric grooves on one side of a thin steel plate. When acoustic wa...Unidirectional acoustic transmission has been investigated in an asymmetric bull's eye structure, which consistes of a subwavelength hole with concentric grooves on one side of a thin steel plate. When acoustic waves impinge normally on the groove side of the asymmetric structure, a strong acoustic transmitted energy flux is observed in the frequency range of 400–450 k Hz, while there is no obvious transmitted energy flux in the same frequency range if the acoustic waves impinge normally on the other side. Thus, a remarkable unidirectional acoustic transmission behavior is exhibited by the current structure. With changing the period of the grooves, it is found that the transmitted acoustic energy flux keeps unchanged while the frequency of the transmitted waves can be modified. The experiments are performed, which has confirmed the unidirectional acoustic transmission behavior in the asymmetric bull's eye structure. The asymmetric bull's eye structure may have potential application in ultrasound diagnosis and therapy.展开更多
基金Projects(51925402,U1710258,52004172)supported by the National Natural Science Foundation of ChinaProject(20201102004)supported by the Science and Technology Department of Shanxi Province,China。
文摘Due to the influence of mining disturbance stress,it is of great significance to better understand the bearing characteristics of fully grouted bolts under different pull-out loading rates.For this purpose,a series of laboratory pull-out tests were conducted to comprehensively investigate the effects of different pull-out loading rates on the mechanical performance and failure characteristics of fully grouted bolts.The results show that the mechanical performance of the anchored specimen presents obvious loading rate dependence and shear enhancement characteristics.With the increase of the pull-out loading rates,the maximum pull-out load increases,the displacement and time corresponding to the maximum pull-out load decrease.The accumulated acoustic emission(AE)counts,AE energy and AE events all decrease with the increase of the pull-out loading rates.The AE peak frequency has obvious divisional distribution characteristics and the amplitude is mainly distributed between 50-80 dB.With the increase of the pull-out loading rates,the local strain of the anchoring interface increases and the failure of the anchoring interface transfers to the interior of the resin grout.The accumulated AE counts are used to evaluate the damage parameter of the anchoring interface during the whole pull-out process.The analytical results are in good agreement with the experimental results.The research results may provide guidance for the support design and performance monitoring of fully grouted bolts.
文摘The aim of the study was to investigate effect of transport times of up to 12 h on pigs＇ welfare. An observation box was located on the 3rd floor of the vehicle. Device to measure temperature, humidity and video camera to monitor pigs＇ behaviors were fitted in the box. Eighteen measurements were performed during two seasons for 4, 8, and 12 h of transport time with three replications. Meat samples were taken from longissimus dorsi （LD） and the carcases were chilled for 24 h at ＋4 ~C for pH determination. To determine cortisol, glucose, lactate, and creatine kinase concentration levels, blood samples were collected before and after transport from 90 pigs and from 20 controls that were not transported for control purposes. To evaluate behavioural alterations, frequency of events and durations were considered. Highest pH24 of 5.99 ＋ 0.29 occurred during summer at 12 h transport time. Cortisol concentrations elevated during short and decreased with an increase of transport time （P 〈 0.001）. Highest and lowest glucose concentrations for winter and summer were at 8 and 12 h transport time, respectively （P 〈 0.01）. Concentrations of lactate and creatine kinase positively correlated with transport time （P 〈 0.002）. Lying, sitting, rooting and vocalization behaviours correlated with transport time （P 〈 0.009）. Certain THI values during summer surpassed normal （〉 74） level during loading. The pH24 value correlated with transport time during summer. Lactate and creatine kinase concentrations increased with an increase in transport time but for Glucose, highest value was at 8 h transport time.
文摘Cat vocal behavior, in particular, the vocal and social behavior of feral cats, is poorly understood, as are the differences between feral and fully domestic cats. The relationship between feral cat social and vocal behavior is important because of the markedly different ecology of feral and domestic cats, and enhanced comprehension of the repertoire and potential information content of feral cat calls can provide both better understanding of the domestication and socialization process, and improved welfare for feral cats undergoing adoption. Previous studies have used conflicting classi- fication schemes for cat vocalizations, often relying on onomatopoeic or popular descriptions of call types （e.g., ＂miow＇）. We studied the vocalizations of 13 unaltered domestic cats that complied with our behavioral definition used to distinguish feral cats from domestic. A total of 71 acoustic units were extracted and visually analyzed for the construction of a hierarchical classification of vocal sounds, based on acoustic properties. We identified 3 major categories （tonal, pulse, and broadband） that further breakdown into 8 subcategories, and show a high degree of reliability when sounds are classified blindly by independent observers （Fleiss＇ Kappa K= 0.863）. Due to the limited behavioral contexts in this study, additional subcategories of cat vocalizations may be identified in the future, but our hierarchical classification system allows for the addition of new categories and new subcategories as they are described. This study shows that cat vocalizations are diverse and complex, and provides an objective and reliable classification system that can be used in future studies.
基金supported by the National Basic Research Program of China(Grant No.2012CB921504)SRFDP(Grant Nos.20110091120040,20120091110001 and 20130091130004)+1 种基金the National Natural Science Foundation of China(Grant Nos.11104139,11274171,11274099 and 11204145)Natural Science Foundation of Jiangsu Province(Grant No.BK2011542)
文摘Unidirectional acoustic transmission has been investigated in an asymmetric bull's eye structure, which consistes of a subwavelength hole with concentric grooves on one side of a thin steel plate. When acoustic waves impinge normally on the groove side of the asymmetric structure, a strong acoustic transmitted energy flux is observed in the frequency range of 400–450 k Hz, while there is no obvious transmitted energy flux in the same frequency range if the acoustic waves impinge normally on the other side. Thus, a remarkable unidirectional acoustic transmission behavior is exhibited by the current structure. With changing the period of the grooves, it is found that the transmitted acoustic energy flux keeps unchanged while the frequency of the transmitted waves can be modified. The experiments are performed, which has confirmed the unidirectional acoustic transmission behavior in the asymmetric bull's eye structure. The asymmetric bull's eye structure may have potential application in ultrasound diagnosis and therapy.
